Re: Kbuild problem
From: Adrian Bunk
Date: Tue Feb 20 2007 - 10:00:03 EST
On Tue, Feb 20, 2007 at 02:56:27PM +0100, Tilman Schmidt wrote:
> Adrian Bunk schrieb:
> > On Sun, Feb 18, 2007 at 12:22:10AM -0500, Kai Germaschewski wrote:
> >> On Sat, 17 Feb 2007, Tilman Schmidt wrote:
> >> > asyncdata.o is only needed for M105 and M101, not for the base
> >> > driver. How do I express in Kbuild that asyncdata.o is to be added
> >> > to gigaset-y only if CONFIG_GIGASET_M105 and CONFIG_GIGASET_M101
> >> > are not both 'n'?
> >> The way this is typically done is via Kconfig. Add a config option
> >> ASYNCDATA (actually something more descriptive/specific would be better),
> >> add a "select ASYNCDATA" to the config options for m101 and m105, and then
> >> you can use CONFIG_ASYNCDATA to decide whether to add asyncdata.o in the
> >> Makefile.
> > One disadvantage of this approach is that in a kernel with
> > CONFIG_GIGASET_BASE=y, you can't later compile and load the usb_gigaset
> > or ser_gigaset modules without rebooting since they require a change to
> > the kernel image.
> You've got a point there. So linking asyncdata.o into the modules that
> need it, as it is currently done, would perhaps be better after all?
> The original problem (asyncdata.o linked in twice, causing duplicate
> symbol definitions) could be fixed with this (admittedly somewhat
> awkward) change to the Makefile (build tested):
> --- linux-2.6.20-mm1-work/drivers/isdn/gigaset/Makefile 2007-02-20 13:39:44.000000000 +0100
> +++ u/drivers/isdn/gigaset/Makefile 2007-02-20 13:38:58.000000000 +0100
> @@ -1,7 +1,10 @@
> gigaset-y := common.o interface.o proc.o ev-layer.o i4l.o
> usb_gigaset-y := usb-gigaset.o asyncdata.o
> bas_gigaset-y := bas-gigaset.o isocdata.o
> -ser_gigaset-y := ser-gigaset.o asyncdata.o
> +ser_gigaset-y := ser-gigaset.o
> +ifneq ($(CONFIG_GIGASET_M101)$(CONFIG_GIGASET_M105),yy)
> +ser_gigaset-y += asyncdata.o
What happens with CONFIG_GIGASET_M101=y, CONFIG_GIGASET_M105=m ?
> obj-$(CONFIG_GIGASET_M105) += usb_gigaset.o gigaset.o
> obj-$(CONFIG_GIGASET_BASE) += bas_gigaset.o gigaset.o
> The alternative would be to always link asyncdata.o into the gigaset
> module whether it's needed or not. "size asyncdata.o" says:
> text data bss dec hex filename
> 4200 0 0 4200 1068 asyncdata.o
> which appears tolerable.
I'm usually someone who likes to avoid including unneeded code in the
kernel, but in this case I'd say KISS - and build it always into the
> Tilman Schmidt
"Is there not promise of rain?" Ling Tan asked suddenly out
of the darkness. There had been need of rain for many days.
"Only a promise," Lao Er said.
Pearl S. Buck - Dragon Seed
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